The question came a day after Robertson blew his second game of the season, giving up five runs after the Yankees handed him a 2-1 lead over the Twins. They eventually lost, 7-2.

That same game, Betances displayed his usual dominance. The 6-foot-8 righty struck out five of the six hitters he faced, showcasing his high-90's fastball and eye-popping slurve.

Through 23 appearances, Betances has an impressive 1.38 ERA and an outstanding 15.4 strikeouts-per-nine-innings rate.

Still, that's not to say Robertson has been bad. The 30-year-old has been effective in replacing the legendary Mariano Rivera, notching 12 saves, a few of them spanning more than a full frame.

But he just hasn't been Betances, who Girardi said kind of reminds him of a young Rivera. In 1996, Rivera's first season as a reliever, he had a 2.09 ERA while acting as John Wetteland's set-up man.

"That year (Rivera) was a guy that we could use for multiple innings and he had been extremely effective just like Dellin has been effective," Girardi said. "So I can understand the comparisons. Obviously, they're different pitchers. I think you can call both power pitchers, but Dellin has the curveball as well."

Rivera lived off throwing what's widely considered the best cut fastball of all time.